The present invention relates to a cooling module for integrated circuit chips and in particular to a cooling unit of a multichip module for effectively removing heat generated by a plurality of integrated circuit chips having high power dissipation mounted on a wiring substrate.
An example of a cooling structure of a multichip module comprising a plurality of integrated circuit chips mounted on a wiring substrate is disclosed in U.S. Pat. No. 4,245,273 issued to Feinbert et al. on Jan. 13, 1981. Such a structure has two gaps in the thermal conduction path extending from an integrated circuit chip to a coolant. One of the gaps is located between the integrated circuit chip and the piston. The other of the gaps is located between the piston and the housing. The thermal conduction across these gaps cannot but rely upon gas in the gaps having an extremely low thermal conductivity. Since a large confronting area is required between the piston and the housing, the length of the piston cannot be reduced, resulting in a long thermal conduction path. As a result, there is a limit to reduction of the thermal resistance between the chip and the coolant.